Digital filter employing PROM for storing positive and negative impulse response values
US4423488A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 9, 1981 |
| Grant date | Dec 27, 1983 |
| Priority date | — |
| Expiry date | Jan 9, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03H17/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A digital filter, having a raised-cosine function in the frequency domain, is implemented in the time domain. For positive and negative impulse inputs, the time domain response of the corresponding frequency domain raised cosine response is created by way of a programmable read-only memory (PROM), the contents of which are selectively addressed by the combination of the contents of a shift register and a counter. The shift register contains a prescribed number of digital samples of successive data bits to be transmitted, while the counter is employed to identify or scan a plurality of successive finite filter response values, based upon the current contents of the shift register. From the memory locations of the PROM corresponding to successively generated address, values are read out representative of the overall or accumulated filter response attributable to the data bits stored in the shift register at the successive sample points determined by the contents of the counter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.